Btrfs: Allocator fix variety pack

* Force chunk allocation when find_free_extent has to do a full scan
* Record the max key at the start of defrag so it doesn't run forever
* Block groups might not be contiguous, make a forward search for the
  next block group in extent-tree.c
* Get rid of extra checks for total fs size
* Fix relocate_one_reference to avoid relocating the same file data block
  twice when referenced by an older transaction
* Use the open device count when allocating chunks so that we don't
  try to allocate from devices that don't exist

Signed-off-by: Chris Mason <[email protected]>

fs/btrfs/ctree.c

@@ -363,7 +363,7 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 			other = btrfs_node_blockptr(parent, i - 1);
 			close = close_blocks(blocknr, other, blocksize);
 		}
-		if (close && i < end_slot - 2) {
+		if (!close && i < end_slot - 2) {
 			other = btrfs_node_blockptr(parent, i + 1);
 			close = close_blocks(blocknr, other, blocksize);
 		}

fs/btrfs/ctree.h

@@ -464,6 +464,7 @@ struct btrfs_space_info {
 	u64 bytes_used;
 	u64 bytes_pinned;
 	int full;
+	int force_alloc;
 	struct list_head list;
 };
 
@@ -589,6 +590,7 @@ struct btrfs_root {
 	int ref_cows;
 	int track_dirty;
 	struct btrfs_key defrag_progress;
+	struct btrfs_key defrag_max;
 	int defrag_running;
 	int defrag_level;
 	char *name;